An electric clothing dryer used in ordinary households uses an electric heater as a heat source which is necessary for drying. Due to the current carrying capacity of a domestic convenience receptacle, its amount of heat is limited, and this causes a bottleneck in reduction of time required for drying clothing. Further, heat used for drying clothing is not reused and is only discharged out, and this is waste of energy.
There is proposed a clothing dryer in which a heat pump is used as a heat source for drying clothing, a portion of drying air is discharged out from a body of the apparatus, thereby reducing the required electricity and achieving high dehumidification efficiency (e.g., see Japanese Patent Application Laid-open No.H7-178289 (pages 4 to 5, FIG. 1)). FIG. 12 shows a conventional clothing drying apparatus described in patent document 1.
In this drying apparatus, a rotation drum 22 is a dry chamber which is rotatably provided in a body 21 of the drying apparatus and which dries clothing 39 in the dry chamber. A rotation drum 22 is driven by a motor 27 through a drum belt 35. A blower 23 sends drying air from the rotation drum 22 toward a circulation duct 26 through a filter 24 and a rotation drum-side air intake 25. The blower 23 is driven by the motor 27 through a fan belt 28.
An evaporator 29 is disposed in the circulation duct 26. The evaporator 29 evaporates a refrigerant, thereby cooling and dehumidifying the drying air. A condenser 30 condenses a refrigerant, thereby heating the drying air flowing in the circulation duct 26. The heated drying air is introduced into the circulation duct 26 and is again returned to the dry chamber. The compressor 31 generates a pressure difference in a refrigerant. A throttle apparatus 32 comprising a capillary tube and the like maintains the pressure difference of the refrigerant. The evaporator 29, the condenser 30, the compressor 31 and the throttle apparatus 32 are connected to one another through pipes 33 to constitute a heat pump apparatus.
However, when the clothing is to be dried using such a drying apparatus, since the temperature of the drying air, a heat exchange loss between the body and outside, a moisture amount included in the clothing to be dried are gradually varied with drying time, it is necessary to always control the optimal amount of heat to be discharged outside. If heat which is greater than the optimal amount of heat to be discharged is discharged outside, the drying time is increased, and the electricity consumption amount is increased.
If the amount of heat of the drying air is excessively increased, pressure in a refrigeration cycle of the heat pump apparatus adversely rises, and there is a problem that the stable operation can not be carried out in the refrigeration cycle.
It is an object of the present invention to provide a drying apparatus which can be operated stably in a refrigeration cycle by cooling the drying air to avoid an influence on the refrigeration cycle caused by increase in the amount of heat of the drying air, and to provide an operating method of the drying apparatus.
It is another object of the invention to provide a drying apparatus capable of shortening the drying time of a subject to be dried, and to provide an operating method of the drying apparatus.
It is another object of the invention to provide a drying apparatus having high reliability and an operating method of the drying apparatus.